…each bulb contains about as much mercury as the dot at the end of this sentence. Multiply that hundreds of times for the bulbs that won’t be recycled, then you do have a environmental nightmare.

It’s true that CFLs contain mercury (about 4 milligrams each), and it’s also true that any amount of mercury pollution is a bad thing. And it’s completely naïve to think that a lot of these bulbs won’t go into the trash – in fact, even the EPA says it’s OK to toss them in the garbage as long as they’re double-sealed in plastic bags.

But the idea that sticking with incandescent light bulbs will help prevent mercury contamination is complete, utter hogwash.

The primary source of mercury pollution in the U.S. is burning coal for electricity generation. Despite EPA efforts to clamp down on emissions, in 2008, U.S. power plants pumped nearly 90,000 pounds of mercury into the air. That’s the equivalent of 10 billion CFL bulbs.

Actually, most of the CFL’s sold by name-brand companies have less than 2.5 milligrams of Hg per bulb. The pressure on the industry to reduce mercury has been responded to, and continues to be responded to. Some of the cheaper no-name and mystery-name bulbs still have higher levels, but we’re way down from even ten years ago.

This was information the Sierra Club acquired about three or four years ago when we created a task force to examine this issue. Mercury is not good, but it must not be allowed to overwhelm our reason when it comes to climate. The mercury in CFL’s is trivial in comparison to the mercury in commercial fluorescent bulbs. We’re still replacing mercury vapor bulbs in most of the U.S. and CFL’s are a big step forward there.

Twenty years ago, coal-fired utilities emitted 5% of U.S. mercury. Today they are the largest source, but the amount of emissions hasn’t changed much. What changed is that all the other sources were substantially cut. What this means is that while utilities are the largest source today, most of the mercury in our environment came from other sources.

When mercury controls do not conflict with carbon reductions and reducing all other pollutants, we should push them. But when there is a conflict, we should be very, very sure of the facts before we decide that mercury is more important than other pollutants. Afer all, we have a large and well documented body count for SO2, but none for mercury.

I believe you have just made an effective argument against coal-burning power plants. Mercury is toxic as well as cumulative; I would avoid both gradual accumulation and acute poisoning. We carefully remove lead-based paints from homes, we carefully remove asbestos found in insulation and floor tile, we stopped the use of DDT and reduced phosphates in detergent, and we put CO and smoke alarms in homes, all to avoid inadvertently poisoning people. We can disagree about “acceptable levels” and zero-tolerance policies, but I would not want my family to be one of the “acceptable casualties” and I could not ask others to.